Reader Sandra Kossacoff shares photos from a cruise to Antarctica with her family in celebration of her 50th birthday.

By , Thursday, Mar 17, 2011, 12:00 PM

Zodiac boats negotiating their way around icebergs in the bay at Booth Island.

(Courtesy Sandra Kossacoff)

A gentoo penguin with the National Geographic Explorer in the background at Port Lockroy.

(Courtesy Sandra Kossacoff)

Howard Fullman and Sandra Kossacoff in a kayak.

(Courtesy Sandra Kossacoff)

The National Geographic Explorer anchored in the bay at Booth Island.

(Courtesy Sandra Kossacoff)

A leopard seal resting on an iceberg.

(Courtesy Sandra Kossacoff)

An Adélie penguin with two chicks.

(Courtesy Sandra Kossacoff)

A blue-eyed cormorant.

(Courtesy Sandra Kossacoff)

Sandra Kossacoff and Howard Fullman in their "fabulous" National Geographic Expedition red parkas on the bow of the ship in an ice-covered bay.

(Courtesy Sandra Kossacoff)

A chinstrap penguin tobogganing.

(Courtesy Sandra Kossacoff)

Orca whales.

(Courtesy Sandra Kossacoff)

Casey (16) and Alex (20) Fullman at Booth Island with the National Geographic Explorer in the background.

(Courtesy Sandra Kossacoff)

Port Lockroy, a former British base during World War II and a scientific research station after the war. The main building has been restored and is now a museum. It also houses the only retail store in Antarctica, which sells souvenirs, and a post office, where we mailed cards bearing Antarctica postage and got Antarctica stamps in our passports.

(Courtesy Sandra Kossacoff)

A sign painted on a building in Ushuaia, Argentina, that describes it as the "World's End," or "Fin del Mundo"; this is where we boarded and disembarked the National Geographic Explorer.

(Courtesy Sandra Kossacoff)

Valparaiso, Chile, a hillside city covered with colorfully painted homes.

(Courtesy Sandra Kossacoff)

It's challenging to drive along the narrow, hilly streets of Valparaiso, Chile.

(Courtesy Sandra Kossacoff)

Colorfully painted homes in Valparaiso, Chile.

(Courtesy Sandra Kossacoff)

The view overlooking the harbor of Valparaiso, Chile, from a balcony near the 21 del Mayo Maritime Museum. From left to right: Casey, Sandra, Alex, and Howard.